Location-based services for mobile wireless devices are only beginning to become adopted. Such mobile wireless devices may include cell phones litigated audio (DAP) or music player, cameras, navigation devices and personal digital assistants (PDAs), as well as more application-specific devices intended for use by service persons and other workers. Cell phones and PDAs are typically small in size, so that the individual user can carry such devices on his or her person, for example, in a belt holster, a backpack, or a book bag. Purpose-specific wireless devices may be incorporated into vehicle-mounted communications equipment or other apparatus used in connection with the service or field visits of the person, although of course service persons may also carry individual cell phones or other wireless devices.
Although the service of tracking geographic locations of wireless devices is known, those services are generally used only to track the locations of individuals such as field service workers or others carrying wireless devices and subscribing to a tracking service. The tracking service may monitor the geographic location of a participating wireless device and report the geographic location of that device to the subscriber concerning, for example, the locations visited from time to time by the user of the wireless device and any entry of the wireless device into so-called red zones, namely, geographic locations that the service subscriber has declared as off-limits to the user, so that the subscriber may later take action as deemed appropriate. In the case of application-specific wireless devices, such devices may monitor additional inputs, such as vehicle speed and ignition on-off status, and periodically report that additional information for supervisory attention. However, such prior systems are not known that can associate a first wireless device by the location of that device relative to the location of at least one other device, for example, a wireless device carried by someone responsible for the whereabouts or movement of the person carrying the first wireless device.